Integrated lead or wireless suspensions used to support the sliders and read/write heads in magnetic disk drives are well known and disclosed, for example, in the Akin, Jr. et al. U.S. Pat. No. 5,796,552 and the Shiraishi et al. U.S. Pat. No. 6,891,700. These devices typically include a flexure mounted to a stainless steel load beam. The flexure typically includes a stainless steel base with a plurality of conductive leads or traces extending between terminal pads on the opposite ends of the device. A layer of polyimide or other insulating material separates the traces from the underlying stainless steel base. Subtractive and additive processes can be used to manufacture these devices. Subtractive manufacturing methods use photolithography and etching processes to form the flexure from laminated material stock having a layer of stainless steel and a layer of conductive material separated by an insulating layer. Additive manufacturing methods use photolithography, deposition and etching processes to add the insulating layer, traces and other structures to a stainless steel base.
The stainless steel layer of the flexure acts as a ground plane for the traces. Because the dielectric layer is usually relatively thin, the traces and ground plane can be coupled. These electrical characteristics can reduce the signal performance characteristics of the traces, especially at high signal frequencies. Approaches for compensating for the impact of the stainless steel layer on the signal performance characteristics are known. For example, the Shiraishi et al. U.S. Pat. No. 6,891,700 discloses holes below the traces through the stainless steel layer of the flexure to lower parasitic capacitance. The Akin, Jr. et al. U.S. Pat. No. 5,796,552 discloses an embodiment having a shield formed by electro-deposition of a metallic film against the dielectric layer below the traces and a conductor shield over the traces.
There remains, however, a continuing need for integrated lead structures providing improved signal performance. To be commercially viable any such structures must be capable of being efficiently manufactured.